Chemistry 1b

Question 1

What does cracking mean?

Answer 1

Splitting up of long-chain hydrocarbons

Question 2

What useful things does cracking make?

Answer 2

Fuels and products like ethene for making plastics

Question 3

What type of reaction is cracking?

Answer 3

Thermal decomposition

Question 4

What does thermal decomposition mean?

Answer 4

Breaking molecules down by heating then

Question 5

How does cracking work?

Answer 5

Firstly they vaporize the long-chain hydrocarbons then the vapour Is passed over a powdered catalyst then the long-chain molecules split apart

Question 6

Most products of cracking are alkanes and unsaturated hydrocarbons alkenes T or F?

Answer 6

True!!

Question 7

What type of bond do alkenes carbons have one of?

Answer 7

Double bond

Question 8

What’s the formula for alkenes?

Answer 8

C=n H=2n

Question 9

How can u test for alkenes?

Answer 9

Put the substance in bromine water and if the bromine water changes colour from orange to colourless it is an alkene

Question 10

What are the two ways to make ethanol?

Answer 10

Ethene+steam→ ethanol

Fermentation (sugar→ carbon dioxide+ ethanol) using yeast

Question 11

What is polymerization?

Answer 11

Joining lots of small alkene molecules together to make a very large long-chain molecules

Question 12

are alkenes or alkanes used to create polymers?

Answer 12

alkenes

Question 13

what do the properties of polymers depend on?

Answer 13

what its made of (the monomers) and the temperature/pressure of the polymerisation

Question 14

what properties could polymers have?

Answer 14

light/stretchy, waterproof, biodegradable and memory foam products can all be made from polymers.

Question 15

polymers are cheap now but prices will rise, why?

Answer 15

they are made of crude oil which will start to become scarce, increasing the price of polymers.

Question 16

why should we recycle polymers?

Answer 16

crude oil will become scarce so less polymers will be made, also most aren’t biodegradable so will fill up space in landfill.

Question 17

how can we get oil from plants?

Answer 17

crush the plant material then press he oil out if the mush, and a centrifuge (spin dryer)

Question 18

why are vegetable oils used in food?

Answer 18

contain a lot of energy, other nutrients such as vitamin E, essential fatty acids that the body uses in many metabolic processes

Question 19

why are vegetable oils used for cooking?

Answer 19

higher boiling point (can cook food at higher temperatures/faster speeds), intensifies flavour/has its own and increases energy we gain from eating it.

Question 20

how many double bonds do monounsaturated fats contain?

Answer 20

only one (mono=1)

Question 21

polyunsaturated fats contain >1 double bond, T or F?

Answer 21

true!!!!!

Question 22

what will unsaturated oils do to bromine water? and why?

Answer 22

they’ll decolourise bromine water because the bromine water will open up the double bonds and join on

Question 23

saturated oils are hydrogenated to harden them, T or F?

Answer 23

false, it is unsaturated oils that are hardened by hydrogenating them

Question 24

how do you hydrogenate an unsaturated oil?

Answer 24

react it with hydrogen in the presence of a nickel catalyst at about 60ᴼC

Question 25

what bonds do the hydrogen react with in hydrogenation?

Answer 25

the double bonds

Question 26

what properties do hydrogenated oils have compared to unsaturated oils?

Answer 26

higher melting points, more solid at room temperature (more viscous) which makes them better as spreads and baking cakes/ pastries

Question 27

you can partially hydrogenate an unsaturated oil, T or F?

Answer 27

TRUE! margarine is partially hydrogenated so it is more solid than an unsaturated oil but not too solid that it becomes difficult to spread.

Question 28

unsaturated oils are used in processed foods instead of butter, T or F?

Answer 28

False, partially hydrogenated oils are used in products like biscuits because they are cheaper and keep longer (have a longer shelf life)

Question 29

what is the downside to partially hydrogenating vegetable oils?

Answer 29

you end up with a lot of trans fats and there is evidence that suggests these are very bad for you.

Question 30

vegetable oils tend to be_____ (11 letters)

Answer 30

unsaturated

Question 31

animal fats tend to be _____ (9 letters)

Answer 31

saturated

Question 32

saturated fats are normally less healthy than unsaturated fats, why?

Answer 32

saturated fats increase the amount of cholesterol in the blood which can block up arteries and increase risk of heart disease)

Question 33

unstaurated oils decrease cholesterol in the blood, T or F?

Answer 33

true! But because of trans fats, partially hydrogenated oils increases the amount of cholesterol, so eating foods with partially hydrogenated oils can increase risk of CHD (coronary heart disease)

Question 34

what is an emulsion?

Answer 34

mixture of oil and water

Question 35

emulsifier molecules have two different ends, one interacts well with water, this end is called?

Answer 35

the hydrophilic end

Question 36

emulsifier molecules have two different ends, one interacts well with oil, this end is called?

Answer 36

the hydrophobic end

Question 37

in what type of emulsion does the emulsifiers coat the surface of oil droplets?

Answer 37

oil-in-water emulsion

Question 38

the hydrophobic end interacts with the oil droplets, T or F?????

Answer 38

True

Question 39

what end interacts well with water in an emulsion

Answer 39

hydrophilic end

Question 40

what keeps the oil droplets from clumping together to form there own layer in the emulsion?

Answer 40

the emulsifiers keep the oil droplets evenly dispersed

Question 41

What are the advantages of emulsifiers?

Answer 41

emulsifiers stop emulsions separating, giving them a longer shelf life, allow companies to produce food that's low in fat but still has a good texture

Question 42

what is the disadvantage of using emulsifiers

Answer 42

some people may be allergic to them

Question 43

what are the three layers of the earth

Answer 43

core, mantle, crust

Question 44

what happens in the mantle

Answer 44

the mantle has all the properties of a solid except it can flow very slowly, this is because radioactive decay takes place here which makes a lot of heat ending in a convection current.

Question 45

what are tectonic plates?

Answer 45

the Earth's crust and upper mantle are split into a number of large pieces called tectonic plates

Question 46

explain Wegner's evidence for continental drift

Answer 46

same types of fossilised animals and plants are found in South America and Africa, South America fits the west coast of Africa like jigsaw, matching rock formations were found in South America and Africa.

Question 47

why wasn't Wegner's theory wasn't excepted for many years?

Answer 47

didn't have any evidence to explain how the continents moved, other scientists had different views, he wasn't an expert geologist.

Question 48

why are earthquakes so difficult to predict? (4 marker)

Answer 48

plates suddenly move, normally move a few centimetres per year, convection currents from radioactive decay cause the movement, don't know what happens under the crust, where forces are building up, cannot measure the forces or when the forces reach there limit.

Question 49

how was carbon dioxide removed from the atmosphere?

Answer 49

plants take in CO₂, CO₂ locked up in fossil fuels, CO₂ reacts with/dissolves in seawater, forms sedimentary rocks

Question 50

in the evolution of the atmosphere what was the volcanic activity phase?

Answer 50

volcanoes kept erupting, giving out steam and CO₂, the early atmosphere was nearly all CO₂, the earth cooled and the water vapour condensed making the oceans

Question 51

in the evolution of the atmosphere what was the plants and algae phase?

Answer 51

green plants converted CO₂ to oxygen through photosynthesis, they died and were buried under layers of sediment among other organisms, carbon and hydrocarbons became locked up in sedimentary rocks as insoluble carbonates and fossil fuels

Question 52

in the evolution of the atmosphere what was the ozone layer phase?

Answer 52

the build up of O₂ killed early organisms and allowed complex organisms to evolve, the ozone layer blocks out harmful UV rays and now there is virtually no CO₂ left

Question 53

what was the Miller-Urey experiment trying to find out?

Answer 53

whether substances made by living things could be formed in Earth's early atmosphere.

Question 54

explain the Miller-Urey experiment

Answer 54

mixed water, ammonia, methane and hydrogen in a sterile flask, heated to make water vapour, electric sparks passed through the mixture, after a week contents were analysed, amino acids were found

Question 55

what are the 6 steps of fractional distillation of air?

Answer 55

filtered to remove dust, cooled to -200 so it becomes a liquid, during cooling water vapour condenses and is removed, CO₂ freezes and is removed, liquefied air then enters fractionating column and is heated slowly, remaining gasses are separated (another column is used to separate oxygen and argon)

Question 56

what does the primordial soup theory state?

Answer 56

the early atmosphere was rich in nitrogen, hydrogen, ammonia and methane and lightening caused a chemical reaction to take place producing amino acids, these amino acids combined to form organic matter, which simple organisms evolved from.